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lhvrrnn Srarns Parent @rrrea ROBERT c. BLAOKALL, or ALBANY, NEW roan.

RELIEF-VALVE FOR LOCOMOTEVE-ENGENES.

SPECIFICATION forming part of Letters Patent No. 283,749, dated August28, 1883,

Application filed July 5, 1882. (No model.)

To all whom it may concern:

Be it known that I, ROBERT C. Bniicnann, of the city and county ofAlbany, and State of New York, have invented certain new and.

.a locomotive boiler and cylinders, showing one side in section forthepurpose of exhibiting underlying parts that are affected by myinvention; Fig. 2, a side elevation of the same, with parts in sectionfor the purpose above described; and Fig. 3, a vertical section of oneform of relief-valve I use for effectuating my invention.

The object of my invention is to remedy a defect now existing inlocomotive-engines, and which is made manifest when, in attempting toavert an accident, the valve motion of the engine is suddenly reversedwhile the engine is moving ahead at a rapid rate of speed. XVheneversuch a reversal is effected the cylinders of the engine operate asair-compressors to fill either the boiler or steam pipesaccording to thecondition of the communicating parts that are open to the saidcylinders-with a large volume of air under great pressure; and if suchreversal occurs after the throttle-valve has been closed, it is alwaysattendedby the blowing-off of the steam-chests, and thereby the engineis left in an unmanageable condition, and, for the time, is a uselesswreck in the presence of a danger that the engineer has been striving toavoid. On the other hand, if the said reversal is effected while thethrottle-valve remains open, the air forced into the boiler by theaction of the pistons of the steam-cylinders soon produces an excessiveaccumulation of pressure in the boiler that will strain it to such adegree that it soon becomes absolutely dangerous.

To remedy this defect my invention consists in providing the engine withan automatic relief-valve placed at any point between the throttle-valveand slide-valves, preferably upon the steam-chest, where it will have afree and open communication with the steam-pipes of the engine only.Said' relief-valve, adjusted to open at a slightly higher pressure thanthe I maximum pressure carried on the boiler, but below the degree ofpressure required toproduce a rupture of the parts, will permit theexcess of air-pressure to escape from the steampipes, and therebyrelieve the structure from the undue strain engendered by thecompression of air by the pistons, and, by means of the saidrelief-valve, a uniform pressure of air, whose maximum point will bewithin the limit of safety, will be maintained in the steammotion, thesteam shut off, and the valve'motion reversed) to serve as an opposingmedium to resist the movement of the pistons of the engine, whichresistance will quickly overcome the momentum of the moving train andstop its motion; and in this respect the volume of air maintained in astate of compres sion in the steam-pipes and steam-chests will, inconjunction with the pistons of the engine, perform the functions of anatmospheric brake in stopping the motion of thp train.

As illustrated in the drawings, A represents the forward end of theboiler of a locomotiveengine; B, the cylinders of the engine; 0, thesteam-chests for containing the slide-valves of the engine; 0, thesteam-chest covers; D, the throttle-valve, E, the main steam-pipe; E,the branch steam-pipes for connecting the pipe E with the cylinders 13,and F the steam-passages for conveying steam into the steamchests. Allof the aforenamed parts, being the usual and well-known constituentparts of an ordinary locomotive-engine, do not of themselves constitutemy invention. It will be seen, and must be clearly understood, that afree and uninterrupted communication is always open between thesteamehests C, steam-pipes E and E, and steampassages F; and, it mustalso be understood, whenever the pistons are reciprocating in thecylinders 13, there is, by the operation of the slide-valves of theengine, an intermittent communication established between the interiorof said cylinders and the steam-chests and steam-pipes G is arelief-valve, which I employ for effectuating my invention, and whichmay be of any suitable style of spring-actuating puppet valve. Saidvalve may be applied at any accessible part of the engine where a directcominunication may be obtained for said valve pipes and steam-chests(while the engine is in.

either with the steam-chests or steam-pipes. As indicated by the arrowmarked 1, the reliefvalve G is placed over the top of the boiler, andcommunicates with the main steam-pipe E where the said pipe extends intothe smokearch of the boiler.- As indicated by arrow 2, said relief-valvecommunicates with the steampassage F, and, as indicated by arrow 3, itis inserted in the cover 0 of one of the steamchests.

Storage-tanks may be connected with the escape-pipes of therelief-Valves for receiving the compressed air discharged from saidvalves, which air may then be utilized when required for. operatingair-brakes in the usual manner.

It will be readily understood by those versed in steam-engineering thatwhile a locomotive with a train of .cars is running in either directionat any considerable rate of speed, if the valve motion of the engine issuddenly reversed it will not immediately effect the stoppage of thetrain, but, on the contrary, the momentum of the train will compel it tocontinue its course for a time and cause the slide-valves to move in adirection that'is contrary to that required by themovement of thepistons, and, as a result of this action, the pistons will continue todraw air into the cylinders through the exhaust-openings and expel it(the air) from the cylinders through the steam-ports into thesteam-chests and steam-pipes, wherein-in the absence of any suitablemeans of escapeit will become so excessively compressed that thesteam-chests will be blown off, and the'locomotive will become an un- 5manageable wreck. By means of relief-valves G, as herein shownand'described, the accumulated pressure in the steam-chests andsteampipes is, at its maximum, kept below the point where it can producea rupturing strain, and- 40 as an incident due to my inventionthecompressed air confined in the steam chests and pipes will resist, themovements of the pistons and quickly stop the motion of the train.

I am aware that relief-valves have hereto-' fore been used in thecylinder-heads and at intermediate points between the slide-valves andpistons of steam-engines for the purpose of preventing the blowing offof the cylinderheads; but while such arrangements require twice thenumber of relief-valves, (one at each end of the cylinder,) they do noteffect the purpose for which my invention is designed. Therefore I donot broadly claim the use of relief-valves on engine-cylinders; but

I claim as my invention- In a locomotive-engine, the combination, withthe steam-chest of an engine-cylinder,

of an automatic relief-valve located intermediately between theslide-valve and throttlevalve, and arranged to operate as and for thepurpose herein specified.

, ROBERT C. BLAGKALL. Witnesses:

Tnos. W. LARWOOD, WILLIAM H. Low.

